Vehicle transmissions are designed to control the application of power output from an engine. Conventional transmissions generally include a gearbox comprising one or more gears that can be selectively engaged with a power input shaft at a number of gear ratios. The crankshaft, or other rotating member or coupling, of an engine may serve as the power input shaft to the transmission. The transmission and gearbox can provide an output speed, torque, power, or other mechanical characteristic that is different from, or the same as, that provided by the power input shaft of the engine. The power output from the transmission is provided, in some form, to the drive wheel, or wheels, of a vehicle.
Most internal combustion engines rely on the transmission to provide optimal torque and vehicle speeds over a range of operating conditions. In contrast, electric vehicles, employing one or more electric motors, have a wide torque band capable of providing maximum torque output at low or high revolutions per minute (rpm). In some cases, an electric vehicle may include a gearbox configured with a planetary gear reduction. This type of gearbox may be designed to match the rpm of the electric motor to that of the drive wheels.
In any event, transmissions can be large, heavy, noisy, and generally require specific mounting interfaces that can dictate the design and/or limit the configuration of a vehicle.